package edu.sju.chenshu.gateway.filter;
import cn.hutool.core.util.StrUtil;
import com.alibaba.fastjson2.JSON;

import edu.sju.chenshu.common.core.constants.CacheConstants;
import edu.sju.chenshu.common.core.constants.Constants;
import edu.sju.chenshu.common.core.constants.HttpConstants;
import edu.sju.chenshu.common.core.domain.Result;
import edu.sju.chenshu.common.core.enums.ResultCode;
import edu.sju.chenshu.common.core.enums.UserIdentity;
import edu.sju.chenshu.common.core.utils.ThreadLocalUtil;
import edu.sju.chenshu.common.redis.service.RedisService;
import edu.sju.chenshu.common.core.domain.LoginUser;
import edu.sju.chenshu.common.core.utils.JwtUtils;
import edu.sju.chenshu.gateway.properties.IgnoreWhiteProperties;
import io.jsonwebtoken.Claims;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.cloud.gateway.filter.GatewayFilterChain;
import org.springframework.cloud.gateway.filter.GlobalFilter;
import org.springframework.core.Ordered;
import org.springframework.core.io.buffer.DataBuffer;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.MediaType;
import org.springframework.http.server.reactive.ServerHttpRequest;
import org.springframework.http.server.reactive.ServerHttpResponse;
import org.springframework.stereotype.Component;
import org.springframework.util.AntPathMatcher;
import org.springframework.util.CollectionUtils;
import org.springframework.web.server.ServerWebExchange;
import reactor.core.publisher.Mono;

import java.util.List;

/**
 * ⽹关鉴权
 *
 */
@Slf4j
@Component
public class AuthFilter implements GlobalFilter, Ordered {
    // 排除过滤的 uri 白名单地址,在nacos自行添加
    @Autowired
    private IgnoreWhiteProperties ignoreWhite;
    @Value("${jwt.secret}")
    private String secret;
    @Autowired
    private RedisService redisService;

    //转发请求前先完成filter中定义的方法
    @Override
    public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain
            chain) {
        ServerHttpRequest request = exchange.getRequest();
        //获取请求接口地址
        String url = request.getURI().getPath();
        // 接口白名单
        if (matches(url, ignoreWhite.getWhites())) {
            return chain.filter(exchange);
        }

        // 不在白名单中,开始身份认证

        //从http请求头中获取token
        String token = getToken(request);
        if (StrUtil.isEmpty(token)) {
            //此处无法抛出异常
            return unauthorizedResponse(exchange, "令牌不能为空");
        }
        Claims claims;
        try {
            claims = JwtUtils.parseToken(token, secret); //获取令牌中信息 解析payload中信息
            if (claims == null) {
                return unauthorizedResponse(exchange, "令牌已过期或验证不正确！");
            }
        } catch (Exception e) {
            return unauthorizedResponse(exchange, "令牌已过期或验证不正确！");
        }
        String userId = JwtUtils.getUserId(claims); //获取jwt中的key
        String tokenKey = getTokenKey(userId);//获取Redis中存储的tokenKey

        //通过redis中存储的数据来控制JWT的过期时间
        boolean isLogin = redisService.hasKey(tokenKey);
        if (!isLogin) {
            return unauthorizedResponse(exchange, "登录状态已过期");
        }

        //代码走到这证明token是正确的且没有过期,开始身份鉴权
        LoginUser user = redisService.getCacheObject(tokenKey, LoginUser.class);
        //如果url中包含/system则是B端管理员的功能,如果身份不是管理员,则认证失败
        if (url.contains(HttpConstants.SYSTEM_URL_PREFIX) &&
                !UserIdentity.ADMIN.getValue().equals(user.getIdentity())) {
            return unauthorizedResponse(exchange, "令牌验证失败");
        }
        //如果url中包含/friend则是C端用户的功能,如果身份不是用户,则认证失败
        if (url.contains(HttpConstants.FRIEND_URL_PREFIX) &&
                !UserIdentity.ORDINARY.getValue().equals(user.getIdentity())) {
            return unauthorizedResponse(exchange, "令牌验证失败");
        }

        return chain.filter(exchange);
    }

    /**
     * 查找指定url是否匹配指定匹配规则链表中的任意⼀个字符串
     *
     * @param url         指定url
     * @param patternList 需要检查的匹配规则链表
     * @return 是否匹配
     */
    private boolean matches(String url, List<String> patternList) {
        if (StrUtil.isEmpty(url) || CollectionUtils.isEmpty(patternList)) {
            return false;
        }
        //如果和白名单中其中一个地址匹配就返回true
        for (String pattern : patternList) {
            if (isMatch(pattern, url)) {
                return true;
            }
        }
        return false;
    }

    /**
     * 判断url是否与规则匹配
     * 匹配规则中：
     * ? 表示单个字符;
     * * 表示⼀层路径内的任意字符串，不可跨层级;
     * ** 表示任意层路径;
     *
     * @param pattern 匹配规则
     * @param url     需要匹配的url
     * @return 是否匹配
     */
    private boolean isMatch(String pattern, String url) {
        AntPathMatcher matcher = new AntPathMatcher();
        return matcher.match(pattern, url);
    }

    /**
     * 获取缓存key
     */
    private String getTokenKey(String token) {
        return CacheConstants.LOGIN_TOKEN_KEY + token;
    }

    /**
     * 从请求头中获取请求token
     */
    private String getToken(ServerHttpRequest request) {
        String token =
                request.getHeaders().getFirst(HttpConstants.AUTHENTICATION);
        // 如果前端设置了令牌前缀，则裁剪掉前缀
        if (StrUtil.isNotEmpty(token) &&
                token.startsWith(HttpConstants.PREFIX)) {
            token = token.replaceFirst(HttpConstants.PREFIX, StrUtil.EMPTY);
        }
        return token;
    }

    //由于gateway 基于 webflux 因此全局异常处理不生效
    private Mono<Void> unauthorizedResponse(ServerWebExchange exchange, String
            msg) {
        log.error("[鉴权异常处理]请求路径:{}", exchange.getRequest().getPath());
        return webFluxResponseWriter(exchange.getResponse(), msg,
                ResultCode.FAILED_UNAUTHORIZED.getCode());
    }

    //拼装webflux模型响应
    private Mono<Void> webFluxResponseWriter(ServerHttpResponse response,
                                             String msg, int code) {
        response.setStatusCode(HttpStatus.OK);
        response.getHeaders().add(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_JSON_VALUE);
        Result<?> result = Result.fail(code, msg);
        DataBuffer dataBuffer =
                response.bufferFactory().wrap(JSON.toJSONString(result).getBytes());
        return response.writeWith(Mono.just(dataBuffer));
    }

    //返回值越小,过滤器越靠前
    @Override
    public int getOrder() {
        return -200;
    }
}